Little more than 50 years after the German ornithologist Wolfgang Makatsch published his book titled No Egg Is Like Another (Kein Ei gleicht dem anderen), new research at the Max Planck Institute for Ornithology in collaboration with the Max Planck Institute of Biochemistry and the University of Hohenheim reveals exactly how right he was. The study describes for the first time the egg albumen and yolk proteomes—that is, all measurable proteins—of a common songbird, the blue tit. It shows that breeding females can fine tune their eggs’ composition to the needs of their young.